Support hose is typically utilized to place some or all of the lower limbs of a wearer under a predetermined containment pressure. One typical example is for use on post-operative patients to prevent swelling. In other instances support hose is commonly utilized on a daily basis to provide support for various medical or aesthetic reasons.
In these and many other applications, fabric is commonly woven today with a stretch characteristic in one or more directions. The stretch of such stretch fabrics is typically achieved through a combination of weaving characteristics and of the filamentary, including elastomeric, yarns or threads utilized in the weaving operation. In most of these applications it is important to control the stretch characteristic to within predetermined limits. To achieve such control requires increased on-line quality assurance testing of the fabric at predetermined times during the manufacturing process in order to determine the consistency of its stretch.
Prior art techniques for measuring stretch have been awkward and clumsy and have not yielded to online monitoring of the production of stretch fabric. In one such example, as shown in U.S. Pat. No. 4,106,313, the material is mechanically pulled to determine stretch. By its nature, this technique is not only awkward but limited in the accuracy of its one-dimensional determination of stretch.